the study of the relations of states with each other and with international organizations and certain subnational entities (e.g., bureaucracies, political parties, and interest groups). It is related to a number of other academic disciplines, including political science, geography, history, economics, law, sociology, psychology, and philosophy. Historical development The field of international relations emerged at the beginning of the 20th century largely in the West and in particular in the United States as that country grew in power and influence. Whereas the study of international relations in the newly founded Soviet Union and later in communist China was stultified by officially imposed Marxist ideology, in the West the field flourished as the result of a number of factors: a growing demand to find less-dangerous and more-effective means of conducting relations between peoples, societies, governments, and economies; a surge of writing and research inspired by the belief that...